EP 0300572 B1 19930310 - METHOD AND APPARATUS FOR INSPECTING APERTURED MASK SHEETS
Title (en)
METHOD AND APPARATUS FOR INSPECTING APERTURED MASK SHEETS
Publication
Application
Priority
GB 8717306 A 19870722
Abstract (en)
[origin: EP0300572A1] An on-line method of inspecting an apertured mask sheet (10) to be formed into a shadow mask for a colour cathode ray tube is disclosed. In one of several embodiments described the mask sheet (10) is linearly scanned by a laser spot (32) transverse to the direction of advancement (30) of the mask sheet. The peak values of the grey levels of the laser light transmitted by the mask sheet are detected and the data is convoluted electronically to form a series of convolution windows (35). The grey levels of the successively formed convolution windows (35) are compared to at least one reference value and an output is produced at least in those cases where an error in the mask aperture size is detected. Other methods of scanning are disclosed which enable the mechanical tolerances of the apparatus to be less stringent. In the case of a low resolution, oversized spot an accurate assessment of the aperture shapes can be made by comparing alternate grey values with its respective reference value.
IPC 1-7
IPC 8 full level
G01M 11/00 (2006.01); G01B 11/24 (2006.01); G01N 21/84 (2006.01); G01N 21/88 (2006.01); G01N 21/93 (2006.01); G01N 21/956 (2006.01); G06T 7/00 (2006.01); H01J 9/14 (2006.01); H01J 9/42 (2006.01); H04N 7/18 (2006.01)
CPC (source: EP KR US)
G01N 21/95607 (2013.01 - EP US); G01N 21/95692 (2013.01 - EP US); G06T 7/0006 (2013.01 - EP US); H01J 9/142 (2013.01 - EP US); H01J 9/42 (2013.01 - EP KR US); G01N 2021/936 (2013.01 - EP US); G01N 2021/95676 (2013.01 - EP US); G06T 2207/10016 (2013.01 - EP US); G06T 2207/30121 (2013.01 - EP US)
Designated contracting state (EPC)
DE ES FR GB IT NL
DOCDB simple family (publication)
GB 2207237 A 19890125; GB 8717306 D0 19870826; CN 1015764 B 19920304; CN 1030846 A 19890201; DE 3879015 D1 19930415; DE 3879015 T2 19930826; EP 0300572 A1 19890125; EP 0300572 B1 19930310; JP 2732858 B2 19980330; JP S6449947 A 19890227; KR 0129169 B1 19980406; KR 890002950 A 19890412; US 4930889 A 19900605
DOCDB simple family (application)
GB 8717306 A 19870722; CN 88104536 A 19880719; DE 3879015 T 19880714; EP 88201518 A 19880714; JP 17933488 A 19880720; KR 880008987 A 19880719; US 22085088 A 19880718